Synthesis Of A New Cathode Materials α-LiFeO₂ For Lithium-ion Batteries By Hydrothermal Stripping Method

Lithium-ion battery has drawn great attention for its high voltage,high energy density,none-memory effect and environmental friendliness and the upgrade of the cathode materials is critical for improving the lithium battery performance.As one kind of new cathode materials Li Fe O2 possesses advantages of wide raw material sources,low-price,environmental friendly,which is coincident with the development needs of the new era.The crystal forms of LiFeO₂ include α,β,γ-type,goethite-type,tunnel structure and corrugated layer.At present,the main synthesis methods are conventional solid-state reaction,iron-exchange method and hydrothermal synthesis.Different synthesis method could directly affect the crystallinity,morphology and particle size distribution of the samples prepared,as well as electrochemical performance.For current research of lithium ferrites,this paper first reportes the nanometer spherical α-LiFeO₂ has prepared by a new synthesized method of hydrothermal stripping with Fe（NO3）3·9H2O and LiOH·H2O as raw materials.Firstly,Fe（Ⅲ）loaded organic phase is prepared by extracting Fe³⁺ solution with naphthenic acid-isooctanol extraction system.Then the Fe（Ⅲ）loaded organic phase and Li⁺ aqueous solution are transferred to a breaker with a certain molar ratio of Li/Fe and precipitate is obtained by heating and reacting a period of time.The resulting product is washed many times with ethanol and distilled water.We finally get high-purity,spherical-like,nanometer sized α-LiFeO₂ crystalline.It has many advantages that this new lithium-ion battery cathode material α-LiFeO₂ is synthesized through the new technique of hydrothermal stripping.Firstly,hydrothermal stripping can effectively control the hydrolysis of metal iron,which will help control the product composition,morphology and particle size in the low-temperature synthesis by adjusting the Li/Fe ratio,changing the reaction temperature,reaction time and concentration of reactants.Research has shown that the α-LiFeO₂ synthesized under the condition of Li/Fe = 30,corg(Fe³⁺)= 0.36 mol·L-1 and reacting at temperature of 240°C for 0.5 h is featured of high purity without b-Li Fe5O8 and b-LiFeO₂ phase,a narrow size distribution with an average diameter of 120 nm and regular spherical-like morphology.It also eliminates the calcination and milling process of the other preparation.Secondly,the regeneration extractant can be reused at the same time the Li⁺ aqueous phase can be reused by adding a cetain amount of lithiun resources and then have reduced the cost.Finally,the α-LiFeO₂ synthesised by hydrothermal stripping can bring about a concept of low cost,environmental friendly and energy-saving production.